This invention relates to a rolling bearing, and more particularly to a rolling bearing suitably used for, for example, a pulley for a compressor for car air-conditioners, and for an idler pulley.
A four-point contact ball bearing having an inner race, an outer race, balls provided between central portions of the two races, and seal members provided between end portions of the two races has heretofore been known (JP-A-2002-130290) as a rolling bearing used for a pulley for a compressor for car air-conditioners.
In a rolling bearing used for a pulley for a compressor for a car air-conditioner, the heat from a compressor body is transmitted the bearing, so that the temperature in an inner portion of the rolling bearing is liable to become high. When a four-point contact ball bearing is used for the same purpose, a slip on the contact portions of the races and balls occurs greatly, and this therefore makes a source of generation of heat. Moreover, when a pulley formed out of a resin is used, the heat in an inner portion of the bearing comes to rarely escape as compared with a case where a pulley formed out of a metal of a high thermal conductivity is used. Therefore, when a four-point ball bearing is used for a compressor in which a resin pulley is used, the temperature of an inner portion of the rolling bearing becomes high. This possibly causes the rubber seals in the rolling bearing to be easily deteriorated, and the seizure-free lifetime of the rolling bearing to be shortened due to the imperfect lubrication of the rolling bearing with grease.
In order to solve the above problems, a rolling bearing disclosed in JP-A-9-210071 in which shielding plates made of metal are used as seal members, and rubber seals are omitted may be used. However, sealing conducted by the metallic shielding plates is a non-contact seal, which is not appropriate for the use of the bearing at high speed.